The use of high energy density (HED) sources, such as explosives, for the purpose of stimulating permeability in hydrocarbon reservoirs has been previously investigated; however, the fracture radius away from the borehole with such technologies has never extended for more than a few feet radially from the borehole. Permeability stimulation in tight formations is currently dominated by the process known as hydraulic fracturing. With hydraulic fracturing, chemically treated water is pumped into the reservoir via a perforated wellbore to hydraulically fracture the rock providing a limited network of propped fractures for hydrocarbons to flow into a production well.
Past investigations and present practice of stimulating permeability in tight formations do not take full advantage of the information gained from detailed analysis of both the formation properties and the customization of a HED system to create the largest permeability zone that is economical. Some systems disclosed herein take into account best estimates of the shock wave behavior in the specific geologic formation and can be geometrically configured and adjusted in detonation time to enhance the beneficial mixing of multiple shock waves from multiple sources to extend the damage/rubblization of the rock to economic distances. Shock waves travel with different velocities and different attenuation depending on physical geologic properties. These properties include strength, porosity, density, hydrocarbon content, water content, saturation and a number of other material attributes.
As such, explosive systems, compositions, and methods are disclosed herein which are designed to be used to fracture geologic formations to provide access to energy resources, such as geothermal and hydrocarbon reservoirs. Some disclosed methods and systems, such as those for enhancing permeability in tight geologic formations, involve the beneficial spacing and timing of HED sources, which can include explosives and specially formulated propellants. In some examples, one or more precursor compositions can be combined to produce a powerful and sensitive explosive composition. The precursor compositions disclosed herein can be shipped and/or stored at lower hazard classes than would be required if combined together as the explosive composition.